IPCC Fifth Assessment Report (AR5)

The Final Draft of the Working Group I contribution to the IPCC Fifth Assessment Report (AR5) is due out at the end of this month. It is under active consideration this week. In anticipation of this event, I want to review the relevance of this group and its work.

Under the auspices of the United Nations (UN), the Intergovernmental Panel on Climate Change (IPCC) is the leading international scientific body for the assessment of climate change. It reviews and assesses the most recent scientific, technical and socio-economic information produced worldwide relevant to the understanding of climate change. It does not conduct any research nor does it monitor climate related data or parameters.

Thousands of scientists from all over the world contribute to the work of the IPCC on a voluntary basis. Review is an essential part of the IPCC process, to ensure an objective and complete assessment of current information. IPCC aims to reflect a range of views and expertise. The Secretariat coordinates all the IPCC work and liaises with Governments. It is supported by WMO and UNEP and hosted at WMO headquarters in Geneva.

Established in 1988, the IPCC has produced four previous Assessment Reports (1990, 1995, 2001, and 2007). The Fifth Assessment Report (AR5) will provide a clear view of the current state of scientific knowledge relevant to climate change. It will comprise three Working Group (WG) reports and a Synthesis Report (SYR). It is the first of these WG reports that is due out at the end of this week.

What will we learn?

We don't know yet, really. The report has not yet be published. Not surprisingly, however, there have been leaks, some of them controversial. It has been published, for example, that the report will show that "carbon dioxide could have a smaller impact on global temperatures than scientists predicted in 2007, opening the possibility greenhouse gas emissions do not have to be radically cut." At the same time it has also been reported that the effects of global warming are more severe than previously thought. Writing the report is an iterative process. How about if we wait and see what it says at the end of the week?

Nonetheless, no one is predicting that AR5 will substantially reverse previous Assessment Reports in the consensus that global warming is caused primarily by human emissions of greenhouse gasses. Pertinent questions will of course include the relative degrees of various forcings, revised rates of change, and likely consequences of climate change. Some of these findings may be somewhat speculative as well, but this report, the most up to date information available, is not expected to call into question the reality of man-made global warming and climate change. If it does, I will be among the first to post such a statement here.